THE PILOT DECIDED TO EXECUTE A PRACTICE AUTOROTATION TO A PASTURE FROM AN ALTITUDE OF ABOUT 1,000 FEET AGL. HOWEVER, DURING THE MANEUVER, WHICH WAS INITIATED IN GUSTY WIND CONDITIONS, THE AIRCRAFT DEVELOPED AN EXCESSIVE SINK RATE. THE PILOT ATTEMPTED TO ABORT THE MANEUVER AND GO AROUND, BUT AFTER APPLYING POWER, HE WAS UNABLE TO ARREST THE SINK RATE BEFORE THE AIRCRAFT TOUCHED DOWN HARD.